Emergency control valve

ABSTRACT

A valve for use in a vehicle for effecting an emergency control of the vehicle should a failure occur in the primary pumping system for the hydraulics or the driving mechanism therefor. The fluid system comprises source of fluid and a pair of pumps, one pump being the primary pump and the second pump being an auxiliary electrically operated pump powered from a battery on the vehicle. Switching means are provided responsive to a change in the flow condition of the fluid caused by a lack of proper performance by the primary pump to effect an activation of the auxiliary pump. The valve is composed of a body having a pair of inlet ports and an outlet port with a chamber being located therebetween and in fluid communication with the pair of inlet ports and the outlet port. A normally closed valve member is provided in the chamber for controlling the main flow of fluid from the primary pump to the outlet port and is openable in response to a predetermined pressure differential in the fluid at the inlet port and the outlet port. A fluid flow rate or flow velocity sensing device is provided for sensing the flow rate or flow velocity of the fluid flowing past the valve and producing a signal in response to a predetermined flow velocity, the switching device being responsive to the signal for controlling the activation of the auxiliary pump.

1 1 Dee.2, 1975 1 1 EMERGENCY CONTROL VALVE John A. Lauek, 1767 Commonwealth Ave, Benton Harbor. Mich 49022 122] Filed: Nov. 26, 1974 [21] Appl. No; 527,248

Related U.S. Application Data [63] Continuation-impart of Ser. No. 424,181, Dec. 12,

1973, abandoned,

[76] Inventor:

Primary Examiner-William L. Freeh Assistant ExaminerGi P. LaPointe Attorney, Agent, or Firm-Woodhams, Blanchard and Flynn 25 T0 ENGINE STAQTEE [57] ABSTRACT A valve for use in a vehicle for effecting an emergency control of the vehicle should a failure occur in the primary pumping system for the hydraulics or the driving mechanism therefor. The fluid system comprises source of fluid and a pair of pumps. one pump being the primary pump and the second pump being an aux iliary electrically operated pump powered from a hattery on the vehicle. Switching means are provided responsive to a change in the flow condition of the fluid caused by a lack of proper performance by the primary pump to effect an activation of the auxiliary pump. The valve is composed of a body having a pair of inlet ports and an outlet port with a chamber being located therebetween and in fluid communication with the pair of inlet ports and the outlet port. A normally closed valve member is provided in the chamber for controlling the main flow of fluid from the primary pump to the outlet port and is openable in response to a predetermined pressure differential in the fluid at the inlet port and the outlet port. A fluid flow rate or flow velocity sensing device is provided for sensing the flow rate or flow velocity of the fluid flowing past the valve and producing a signal in response to a predetermined flow velocity. the switching device being responsive to the signal for controlling the activation of the auxiliary pump.

10 Claims, 11 Drawing Figures ENGINE TRAISHlSSlOll US. Patent Dec. 2, 1975 Sheet 1 of4 3,923,423

' T0 ENGINE STAPTER US. Patent Dec. 2, 1975 Sheet 2 Of4 3,923,423

US. Patent Dec. 2, 1975 Sheet 3 of4 3,923,423

EMERGENCY CONTROL VALVE This application is a continuation-in-part of US. Ser. No. 424,l8l, filed Dec. l2, W73 now abandoned.

FIELD OF THE INVENTION This invention relates to a valve and, more particu larly, relates to a valve for use in vehicles having a pair of pumps, one pump being a primary pump and the other pump being an auxiliary pump activated upon a failure in the operation of the primary pump to maintain an emergency control of the vehicle during periods of time that a lack of proper performance exists in the primary pump.

BACKGROUND OF THE INVENTION The presently known warning systems on vehicles, particularly large earth moving type vehicles, is unsatisfactory in that there is a lack of automatic equipment which will effect a maintenance of the hydraulic system in operable condition should there be a failure in the primary pumping system or driving mechanism therefor. The presently known systems have usually three methods to warn the operator of a primary pump failure. One type of system is a buzzer which warns the operator that there is a failure in the primary steering system. The second type of warning is a red light which is supposed to be noticed by the operator to warn him of a primary steering failure. The third warning is the operators inability to steer the vehicle. In all three instances, the operator must manually operate a switch to turn on an emergency pumping system to reactivate the hydraulics to supply power to the primary steering system. In some cases, the operator will panic as a result of events happening too fast for him to remember to manually activate the switch and, as a result, an accident is a highly likely occurrence. Accordingly, it is desirable to have an automated control which automatically activates an emergency pumping system when the flow of fluid from the primary steering pump falters.

Ron U.S. Pat. No. 3,762,492 discloses an automatic responsive system for activating an auxiliary pump when the main pump fails to discharge sufficient flow. A flow sensing apparatus is located in the discharge line of the main pump and the electrical output from the flow sensing means is connected to circuitry associated with the auxiliary pump for automatically activating the auxiliary pump in response to a predetermined decay in the flow discharge by the main pump. It is desirable, however, to have a single valve which can be placed into the circuit, which valve has a pair of inlet ports, one being connected to the main pump and the other being connected to the auxiliary pump. The outiet port from the valve is then connected in circuit with the load. As a result, this invention relates to the particular characteristics of a valve and not to the characteristics ofthe overall system. The valve disclosed in the present application, while disclosed in an emergency control system for controlling the steering system on large offhighway vehicles, it is to be understood that the valve can be utilized in numerous other fluid operated systems wherein it is necessary that a secondary pumping system be automatically activated upon the failure of the primary pumping system.

MacDuff, US. Pat. No. 3,733,817, discloses another system which includes duplicate sets of hydraulic lines and pump rcserviors and a pair of shuttle valves for switching the flow from one set of lines and reservior to 2 the other depending upon which pump is providing fluid power. The system includes flow sensing means to determine when the primary system has failed. The flow sensing means senses the flow therethrough and is connected to the auxiliary pump for rendering the auxiliary pump inoperative in response to a predetermined flow through the primary fluid circuit. The auxiliary pump becomes operative in the event that the predetermined flow through the primary circuit is not attained.

U The circuitry disclosed in the MacDuff patent is quite complicated and, further, does not disclose the particu iar characteristics and structure of the valve arrange ment disclosed herein. As a result, the valve disclosed herein renders the system much more simple and less expensive to build and maintain.

Accordingly, it is an object of this invention to provide a valve for automatically controlling the activation of an emergency pumping system when the flow rate of fluid from the primary pumping system is slightly less than the flow rate through the valve at engine idle speed where the engine is utilized to drive the primary pumping system. It is a further object of this invention to provide a valve which is compact and which will be utilizable in existing systems with a minimum of installation considerations. It is a further object of this invention to provide a valve which is easily manufactured and at a minimum cost and is easily maintained in satisfactory operation.

SUMMARY OF THE INVENTION In general, the objects and purposes of the invention are met by providing a valve for use in a vehicle having a source of fluid, a first pumping means operative by a driving mechanism for the vehicle and a second pumping means operative from a power source on the vehicle. Switching means are provided responsive to a change in the flow rate condition caused by a lack of proper performance of the first fluid pumping means to effect an activation of the second fluid pumping means. The valve is composed of a body having a pair of inlet ports and an outlet port and chamber means being located therebetween and in fluid communication with the pair of inlet ports and the outlet ports. A normally closed valve means is provided in the chamber means for controlling the main flow of fluid from the first pumping means to the outlet port and being openable in response to a predetermined pressure differential in the fluid at the inlet port and at the outlet port. A fluid velocity sensing means is provided for sensing the flow rate of flow velocity of the fluid flowing past the valve and producing a signal in response to a predetermined flow velocity. The switching means is responsive to the signal for controlling the activation of the second pumping means.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and purposes of this invention will be apparent to persons acquainted with valves of this general type upon reading the following specification and inspecting the accompanying drawings, in which:

FIG. 1 is a schematic fluid and electrical circuit diagram for a system utilized in a vehicle to control the steering thereof;

FIG. 2 is a central sectional view through the valve;

FIG. 3 is an illustration similar to FIG. 2 except with the valve components in a slightly shifted position;

FIG. 4 is an illustration similar to FIG. 3 with the valve components in a still further shifted position,

FIG. is an illustration similar to FIG. 4 with the valve components in still another shifted position;

FIG. 6 is an illustration similar to FIG. 5 with the valve components in a still further shifted position;

FIG. 7 is a sectional view taken along the line VII- VII of FIG. 2;

FIG. 8 is a sectional view taken along the line VIII- VIII of FIG. 7;

FIG. 9 is a central sectional view through a modified construction of the valve;

FIG. 10 is an illustration similar to FIG. 9 with the valve components in a slightly shifted position; and

FIG. 11 is an illustration similar to FIG. 9 with the valve components in a still further shifted position.

Certain terminology will be used in the following description for convenience in reference only and will not be limiting. The words up", down", right" and "left" will designate directions in the drawings to which reference is made. The words in" and out will refer to directions toward and away from, respectively, the geometric center of the device and designated parts thereof. Such terminology will include the words above specifically mentioned, derivatives thereof and words of similar import.

DETAILED DESCRIPTION While the invention disclosed herein arose primarily out of a need to improve the automatic emergency control system controlling the steering system on large rubber tired vehicles, such as earth-moving vehicles, it is to be understood that the valve disclosed hereinafter is utilizable for controlling hydraulically actuated brakes on a vehicle and numerous other fluid operated systems wherein it is necessary that a secondary pumping system be automatically activated upon the failure of the primary pumping system. Accordingly, the following disclosure is not to be limiting to the disclosed environment.

Referring now to the drawings, particularly FIG. 1, a fluid circuit 10 for controlling the operation of a steering system on the vehicle is composed of a reservior l l, a main suction pipe 12 branching into a pair of suction pipes 13 and 14. The inlet port to the main pump 16 is connected to the suction pipe 14. The outlet port from the main pump 16 is connected to an inlet 17 to a valve 18 through a pipe 19. An outlet 21 from the valve 18 is connected to the primary steering system in the vehi cle.

The auxiliary pump 22 has an inlet which is connected to the suction pipe 13 and an outlet that is connected through a pipe 23 and check valve to a second inlet port 24 on the valve 18. The check valve 20 is oriented to prevent a back flow from the valve 18 to the auxiliary pump 22. The auxiliary pump 22 is, in this embodiment, electrically operated whereas the main pump 16 is driven by the engine for the vehicle through 3. schematically illustrated drive train 26. It is to be recognized that the auxiliary pump 22 can be driven from a power source other than an electrical power source on the vehicle.

The electrical circuit 25 on the vehicle is composed of a conventionally battery 27 and an ignition switch 28 for controlling a starter motor associated with the vehicle engine. After the engine is started, the main pump 16 is driven by the engine through the gear train 26 to supply fluid from the reservior 11 through the valve 18 to the primary steering system. A normally open pump control switch 29 is connected to the battery and is adapted to supply power, when closed, through a switch 31 to the auxiliary pump 22. It is to be noted, that the switch 31, details of which will be explained in more detail below, is open after the engine is running at least at idle speed and the main pump 16 is supplying fluid to the steering system. The operator of the vehicle must close the switch 29 to permit operation of the transmission system to control the movement of the ve hicle. If desired, the switch 29 may be connected through a schematically illustrated connection 32 to the vehicle transmission to permit operation thereof only after the switch 29 has been closed. It is to be recognized, of course, that other control arrangements can be utilized to ensure that the switch 29 will be closed before the vehicle is movable.

Referring now in more detail to the valve 18 (FIG. 1), the valve 18 is composed of a check valve 36 positioned between the valve inlet 17 and the valve outlet 21. It is to be noted that there is another fluid connection between the inlet 17 and the outlet 21 without passing through the check valve 36. A fluid flow rate or flow velocity sensing mechanism 37 is connected in this other fluid connection and in parallel with the check valve 36. A reciprocal member 38 is reciprocal in response to a predetermined flow rate or flow velocity to effect an opening of the above-mentioned switch 31. The reciprocal member 38 is designed to be moved rightwardly (FIG. 1) when the fluid flow-through the valve is at a velocity which corresponds to the engine running at idle speed. As a result, when the engine speed falls below idle speed, the reciprocal member 38 will move Ieftwardly under the influence of a spring 39 and cause a closing of the switch 31 iii-"response thereto.

Referring now to FIG. 2, the valve 18 is composed of a body 41 in which are provided the aforementioned inlet ports 17 and 24 and the outlet port 21. A bore 42 is provided in the body 41 and is larger in diameter than the passageway defined by the inlet 17 to define a valve seat 43 adjacent the inlet port 17. The bore 42 opens outwardly of the body 41 at a side remote from the inlet port 17. A cap 44 closes the opening and a seal 46 is provided to prevent the escape of fluid therepast to thereby define a chamber 45. A conventional snap ring 47 is used in this particular embodiment to hold the cap 44 in the opening and to prevent a relative movement between the cap 44 and the body 41. The cap 44 has a pair of spaced legs 48 and 49 (FIGS. 2 and 7) thereon which extend toward the inlet port 17 a short distance. Only the leg 49 is illustrated in FIGS. 2 to 6 while both of the legs 48 and 49 are illustrated in FIG. 7.

Referring now to FIGS. 7 and 8, the body 41 has a pocket 51 therein located on the side thereof with an opening 52 being provided in the bottom of the pocket 51 to provide communication between the pocket 51 and the space 53 between the pair of legs 48 and 49 on the cap 44. A bearing retainer 54 is mounted in the opening 52 and rotatably supports a shaft 56 therein. An operating lever 57 is secured to one end of the shaft 56 and depends downwardly between the legs 48 and 49 on the cap 44. A microswitch housing 58 is secured to the bearing retainer 54 by any convenient means, such as screws 59. In this particular embodiment, the screw 59 serves to support the microswitch housing 58 for pivotal movement about the axis of the screw 59. An inverted U-shaped bracket 61 is secured by a plurality of screws 62 to the bearing retainer 54 and straddles the microswitch housing 58. The leg 63 of the bracket 51 has a recess 64 therein receiving a spring 66 which extends between the bottom of the recess and a surface of the microswitch housing 58. An opposite leg 67 of the bracket 61 has a threaded opening 68 therethrough receiving an adjusting screw 69 therein which is locked in a fixed position by a locking nut 71. The end of the screw 69 remote from the head engages a surface of the microswitch housing opposite the surface engaged by the spring 66. As a result, an adjustment of the screw 69 will effect a pivotal movement of the microswitch housing 58 about the axis of the screw 59. The end of the shaft 56 remote from the operating lever 57 has a flattened surface 72 thereon engageable with the mechanism for operating the microswitch inside the microswitch housing 58. The microswitch inside the microswitch housing corresponds to the switch 31 schematically illustrated in FIG. 1. A cover 72 is adapted to cover the pocket 51 as is securable thereon by any convenient means, as by screws 73.

Referring again to FIG. 2, a spring retaining member 74 is mounted in the chamber 45 against the left end of the legs 48 and 49 on the cap 44 and has a diameter approximately equalling the diameter of the chamber 45. The spring retainer 74 has an opening 76 through the center thereof. The spring retainer 74 is, however, lo cated to the right of a passageway 77 which connects the chamber 45 to both the inlet port 24 and the outlet port 21.

The check valve member 36 is composed of a hollow sleeve member 78 movable axially of the chamber 45. A valve face 79 is provided on the sleeve member 78 at the left end thereof and is adapted to engage the valve seat 43 on the body 41. In this particular embodiment, the main portion of the sleeve member 78 is spaced from the wall of the chamber 45 by radially extending spacers 81 mounted around the periphery of the sleeve member 78. The circumferential spacing between the spacers 81 will facilitate a flow of fluid therebetween from the inlet port 17 in the direction of the arrow A in FIG. 2 when the sleeve member 78 is shiftecl tn the rightwardmost position as illustrated in FIGS. 5 and 6:

A spring 82 is provided between the spring retainer 74" t and the right end of the spacers 81 to urge the valve face 79 on the sleeve member 78 into engagement with the valve seat 43 on the body 41. A plurality of openings 83 are provided in the wall of the hollow sleeve member 78 to connect the interior thereof to the exterior thereof particularly between the circumferentially spaced spacers 81. A radially inwardly extending shoulder 84 is provided on the interior of the hollow sleeve member 78 adjacent the inlet port end thereof.

The fluid velocity sensing mechanism 37 is composed of a hollow sleeve member 86 disposed in the interior of the hollow sleve member 78. The diameter of the sleeve 86 is larger than the diameter of the opening defined by the shoulder 84. An inclined surface 87 is provided on the hollow sleeve member 86 adjacent the left end thereof and is adapted to engage and move away from the shoulder 84. A rod 88 is fixedly secured to the hollow sleeve member 86 and extends rightwardly therefrom through the opening 76 in the spring retainer 74. In this particular embodiment, the hollow sleeve member 86 has a recess 89 in the right end thereof which is adapted to receive an enlarged portion 91 on the rod 88, which enlarged portion 91 is retained in the recess 89 by a snap ring 92 fixed in a corresponding recess in the interior of the hollow sleeve 86. A spring 95 is provided between the spring retainer 74 and the enlarged portion 91 to urge the hollow sleeve member 86 and its surface 87 into engagement with the shoulder 84. As a result, a relative reciprocating movement between the hollow sleeve member 86, the hollow sleeve member 78 and the body 41 will produce a reciprocat ing movement of the rod 88 in the opening 76 of the spring retainer 74. The rod 88 is adapted to engage the operating lever 57 of the electrical microswitch system discussed above.

A plurality of openings 93 are provided in the wall of the hollow sleeve member 86 to provide fluid communication between the interior of the hollow sleeve member 86 and the passageways 83 in the wall of the hollow sleeve member 78. The location of the openings 93 is to the right of the enlargement 91 on the rod 88 and to the left of the inlet port end of the hollow sleeve member 86. A valve seat 94 is provided on the interior of the hollow sleeve member 86 adjacent the left end thereof and is engaged by a ball 96. The ball 96 is biased into engagement with the valve seat 94 by a spring 97. In this particular embodiment, the spring 97 extends between the enlargement 9] on the rod 88 and the ball 96. The diameter of the ball 96 is preferably less than the internal diameter of the interior of the hollow sleeve member 86 so that when the wall 96 is moved rightwardly away from the valve seat 94, fluid will be permitted to flow past the ball 96 and through the aligned openings 93 and 83.

If desired, the operating lever 57 for the microswitch assembly discussed above can incorporate a mechanism for assuring that when the rod 88 is moved away therefrom, namely to the left, the operating lever 57 will be moved to a position to effect a closing of the contacts of the microswitch 31, schematically illustrated in FIG. 1. This can be easily accomplished by providing an externally threaded plug 98 in an internally threaded opening 99 in the cap 44 with a spring 100 extending between the plug 98 and the operating lever 57. The compression of the spring 100 can, of course, be adjusted by moving the plug 98 in the internally threaded opening 99 closer to or away from the operating lever 57 to permit a precise or fine" adjust- .-jnent for controlling the flow rate or flow velocity .which will effect a full shifting of the hollow sleeve 86 t the full rightmost position. A selection of the size of the spring will permit a rough control of the flow rate or flow velocity to effect a shifting of the hollow sleeve 86,

OPERATION f g ihe operation of the device embodying the invention has been indicated somewhat above, a br e summary of the operation will be given below for convemence.

In order to initiate an operation of the steering syst, It IS necessary t start the engine. This is accomphshed by momentarilyclosing the ignition switch 28 to energize the engine starter. Once the engine has become started and is beginning to run at idling speed, the main pump 16 is drawing a supply of fluid from the re- SFl'VlOl' 11 through the suction pipe 12 and 14 and dehvenng same through the pipe 19 to the inlet 17 of the valve 18. The strength of the spring 97 is sufficiently weak that the ball 96 will move rightwardly from the FIG. 2 position to permit fluid to flow therepast as indicated by the arrow B in FIG. 3 and through the aligned openings 83 and 93. Once the engine has reached idling speed and fluid is flowing into the inlet port 17 of the valve 18, the pressure drop occurring across the ball 96, which is directly proportional to the velocity of the fluid flowing therepast, will generate a force greater than the return force of the spring 95 thereby causing the hollow sleeve member 86 to slide to the position illustrated in FIG. 4. Since the cross sectional area of the sleeve 86 is greater than the initially exposed portion thereof in the opening defined by the shoulder 84, a shifting of the sleeve 86 to the right will be very quick. It is to be noted that the fluid flow past the ball in the direction of the arrow B in FIG. 3 and thence through the aligned passageways 93 and 83 becomes closed in FIG. 4. The spring force of the spring 95 is selected so that the force required to move the hollow sleeve member 86 throughout its length of travel will be less than the force required to move the hollow sleeve member 78 and its valve face 79 from engagement with the valve seat 43. As a result, the strength of the spring 95 is less than the strength of the spring 82.

Once the valve is in the FIG. 4 position, it is to be noted that the rod 88 has engaged the lever arm 57 and has moved same causing the rotation of the shaft 56. This effectively results in an openning of the contacts 31 (FIG. 1). Fluid will not flow past the check valve 36 because the check valve 36 is still closed and the passageways 93 and 83 are no longer aligned. Eventually, however, a fluid pressure will build up in the system due to continued operation of the engine to effect a shifting of the check valve 36 to the position illustrated in FIG. 5 so that the main flow of fluid occurs as indicated by the arrow C therein. It is to be noted that a shifting of the check vlve 36 rightwardly will realign the openings 93 and 83 so that fluid will again flow past the ball 96 generating the necessary pressure drop to keep the hollow sleeve member 86 shifted rightwardly with respect to the check valve 36.

If the operator intends to move the vehicle, it will be necessary to first close the manually operated switch 29 (FIG. 1). As stated above, the switch 29 can be activated for a multitude of purposes, such as releasing a lock on the transmission system or effecting a release of the emergency brake system which is normally applied when the vehicle is at rest and/or unattended. In any event, a closing of the switch 29 will not result in an activation of the auxiliary pump 22 due to the fact that the components of the valve 18 are now in the position illustrated in FIG. 5 and the contacts 31 (FIG. 1) inside the microswitch housing 58 are in the opened position. However, the system is now set to operate automatically should there be a failure in the primary pumping system 16.

Should there be a failure in either the engine or the primary pump 16 driven thereby. a pressure differential may be maintained between the inlet port 17 and the outlet port 21. As a result, the check valve 36 will remain for a period of time in the position illustrated in FIG. 5 as a result of this pressure differential. However, the flow rate or velocity of the fluid flowing through the valve may diminish very rapidly. Since the hollow sleeve member 86 and its internal construction is reciprocable in response to the velocity of the fluid flowing through the valve, a drop in the fluid velocity will result in the spring 95 returning the hollow sleeve member 86 to its leftwardmost position inside the hollow sleeve member-78, namely a position illustrated in FIG. 6. This will cause a movement of the rod 88 away from the operating lever 57 to effect a closing of the contacts 31 (FIG. 1) located inside the microswitch housing 58.

As a result, the auxiliary pump 22 is immediately activated before the primary pump becomes completely inoperative. As a result, pressurized fluid is introduced through the pipe 23 and check valve 20 to the inlet 24 of the valve 18. Pressurized fluid entering the inlet 24 will pass through the passageway 27 to close the check valve 36 if it has not closed already and to move the ball 96 into tight engagement with the valve seat 94. As a result, all pressurized fluid entering the inlet 24 will pass through the outlet port 21 to the steering system to maintain a continued operation thereof.

ALTERNATE CONSTRUCTION In the embodiment discussed above, the flow control valve 18 performed its function before the check valve 36 moved rightwardly away from the valve seat 43. In this particular embodiment, the valve member is moved from its seat at the beginning of flow through the inlet port connected to the primary pump 16.

More particularly, the yalve body has a pair of inlet ports 111 and 112 and an outlet port 113. Each of the inlet ports 111 and 112 and the outlet port 113 is connected in fluid circuit with a chamber 114 through a passageway 116. The inlet port 112 has embodied therein a check valve 117 which corresponds to the check valve 20 appearing in FIG. 1. A hollow sleeve 1 18 is inserted into an opening 1 19 in the inlet port 112 with the inner end of the sleeve 118 defining a valve seat 121. The sleeve 118 is fixed to the wall of the opening 119 by any convenient means, such as a press fit. The check valve 117 has a hollow-cup-shaped body 122 adapted to slide back-and-forth within the opening 1 19 in the inlet port 112. The cup-shaped body 122 has a cylindrical wall 123 and a bottom wall 124. A valve face 126 is provided on the bottom wall 124 of the valve body 122 and is adapted to engage the valve seat 121. An annular cut-out 127 is provided in the wall 123 so that there is a spacing between the peripheral surface on the cut-out portion 127 and the internal surface of the opening 119. A plurality of openings 128 are provided in the peripheral surface of the cut-out 127 so that communication is provided between the area immediately adjacent the periphery of the cut-out portion 127 and the interior of the check valve 117. A spring 129 is mounted internally of the check valve 117 and engages at one end a shoulder 131 in the interior of the body 122 and, at the other end, a shoulder 132 on the valve body 1 10. The spring 129 serves to bias the valve face 126 into engagement with the valve seat 121.

The chamber 114 is composed of a bore 133 which is larger in diameter than the passageway defined by the inlet port 111. The bore 133 opens outwardly of the valve body 110 at a side remote from the inlet ports 111 and 112 but in axial alignment with the inlet port 111. A cap 134 closes the opening 133 and a seal 136 is provided to prevent the escape of fluid therepast to thereby define the chamber 114. A conventional snap ring 137 is used in this particular embodiment to hold the cap 134 in the opening and to prevent a relative movement between the cap 134 and the valve body 1 10. The cap 134 has, like the cap 44 in the previously discussed embodiment, a pair of spaced legs (only the leg 138 being illustrated in FIGS. 9 to 11) thereon which extend toward the inlet port 111 a short distance. An externally threaded plug 139 is provided in an internally threaded opening 141 in the cap 134. A recess 142 is provided in the end of the plug 139 facing the chamber 114. A spring 143 is mounted in the recess 142 and extends outwardly therefrom into the chamber 114. A plate 144 having a centrally disposed opening 146 therethrough is mounted in the bore 133 and engages the left end of the legs (only the leg 138 being illustrated in FIGS. 9 to 11) on the cap 134. The plate 144 is urged by the legs 138 into engagement with the shoulder 147 on the valve body 110 and is fixed with respect to the valve body 110. The opening 146 is axially aligned with the recess 142 in the plug 139.

The switch arrangement 148 is identical to the switch arrangement disclosed in the embodiment discussed above. Accordingly, further comment about the switch arrangement 148 is believed to be unnecessary. In this embodiment, the shaft 149 connected to the switch (not illustrated) extends outwardly from the switch and has an arm 151 secured thereto and extending downwardly into engagement with the free end of the spring 143.

Referring now to the inlet port 111 and the valve construction contained therein, which inlet is connected to the main pump 16 illustrated in FIG. 1, the inlet port 1 1 1 is narrowed down to define a narrow passageway 156. The narrow passageway communicates between the inlet port 111 and the chamber 114. The edge 157 between the narrow passageway 156 and the chamber 114 defines a valve seat.

A valve member 158 is mounted for reciprocal movement in the chamber 114 toward and away from the valve seat 157. The left end of the valve member 158 has a chamfered face 159 thereon defining a valve face. The valve face 159 is adapted to engage the valve seat 157. A projection 161 on the left end of the valve member 158 projects leftwardly into the narrow passageway 156. The projection 161 has an annular groove 162 therein defining a peripheral edge 163 at the forwardmost end thereof. The spacing between the peripheral edge 163 of the projection 161 is spaced from the internal wall of the narrow passageway 156 a small distance, such as 0.062 inches. The peripheral edge 163 is also spaced leftwardly across the groove 162 from the valve face 159.

A recess 166 is provided in the left end of the valve member 158. A control member 167 is slidably mounted in the recess 166. The control member 167 has an extension 168 which extends rightwardly from the right end of the valve body 158 and extends through the opening 146 so that the free end is spaced from but almost engages the arm of the switch arrangement 148 when the valve face 159 is in engagement with the valve seat 157. A hole 169 extends longi tudinally through the center of the control member 167 to vent the space between the left end of the control member 167 and the bottom of the recess 166. A spring 171 is provided in the recess 166 between the left end of the control member 167 and the bottom of the recess 166. The strength of the spring 171 is twice as strong as the spring 143 in this particular embodiment. However, it is to be recognized that the strength of the spring 171 is always greater than the strength of the spring 143 but that other ratios of strength may be utilized to create different conditions upon which the valve face 159 is moved away from the valve seat 157.

Although the operation of the alternate embodiment of FIGS. 1 to 11 has been indicated somewhat above, a brief summary of the operation will be given below for convenience.

In order to initiate an operation of the steering system, the same procedures that were described in the operation section above are to be followed. That is, the engine is started by momentarily closing the ignition switch 28 (FIG. 1) to energize the engine starter. Once the engine has become started and is beginning to run at idling speed, the main pump 16 is drawing a supply of fluid from the reservior 11 through the suction pipe 12 and 14 and delivering same through the pipe 19 to the inlet port 111. The fluid will flow through the inlet port 111 and into the annular groove 162 between the peripheral edge 163 and the internal surface 156 of the narrow passageway 156. The initial flow of fluid will move the valve face 159 away from the valve seat 157 a distance equal to the small spacing between the right end of the extension 168 and the control member 167 and the arm 151 on the switch arrangement 148. As the flow increases past the orifice defined by the spacing between the peripheral edge 163 and the internal surface of the narrow passageway 156, a sufficient pressure drop is created to move the valve member 158, including the control member 167, against the arm 151 of the switch arrangement 148 to cause the switch 31 to open. It is to be noted that even though the arm 151, when moved to the position illustrated in FIG. 10, effects an opening of the switch, the projection 161, particularly the peripheral edge 163, is still located within the narrow passageway 156. This is due to the fact that the spring pressure 143 is one-half the spring pressure for the spring 171. As a result, the spring 143 will be compressed to its maximum extent before any compression at all will occur in the spring 171. As the flow continues to increase, a sufficient pressure drop will occur across the orifice between the peripheral edge 163 and the internal surface of the narrow passageway 156 to effect a compression of the spring 171 so that the valve member 158 is moved so that the right end thereof comes into engagement with the plate 144 (see FIG. 11). Further, the pressure will be sufficient to compress the spring 171 to permit a relative movement between the control member 167 and the valve body 158. As a result, the peripheral edge 163 is moved out of the narrow passageway 156 to minimize the flow restriction generated by the presence of the peripheral edge within the narrow passageway 156.

In the event that the flow from the main pump 16 diminishes to a value below a predetermined value, the valve body 158 will immediately shift to the left under the effect of the springs 171 and 143 to permit the spring 143 to return the arm 151 to the position illustrated in FIG. 9 to cause a closing of the switch 31 as illustrated in FIG. 1 to activate the auxiliary pump 22. Pressure then will be supplied to the inlet port 112 of a sufficient magnitude to open the check valve 117 to supply pressure to the chamber 114. The pressure within the chamber 114 will cause the valve body 158 to move further leftwardly, if the valve face 159 is not already in contact with the valve seat 157, to cause a firm contact between the valve face 159 and the valve seat 157. The fluid pressure will then flow out of the outlet 1 13 to the load. It is to be noted that the foregoing response of the valve body is to a decrease in the flow from the main pump 16 and not to a variation in the pressure from the main pump.

Although particular preferred embodiments of the invention have been disclosed in detail for illustrative purposes, it will be rocognized that variations or modifications of the disclosed apparatus, including the rearrangement of parts, lie within the scope of the present invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as fol lows:

l. A valve for use in a system having a source offluid, a first fluid pumping means operative by a driving mechanism and a second auxiliary fluid pumping means and switching means responsive to a change in the flow condition of said fluid caused by a lack of proper performance of said first fluid pumping means to effect an activation of said second fluid pumping means, said valve comprising:

means defining a body having an inlet port and an outlet port spaced from said inlet port;

chamber means located in said body and between and in fluid communication with said inlet port and said outlet port, said chamber means including means defining a first valve seat adjacent said inlet port;

a first elongated hollow valve member slidably disposed in said chamber means and being adapted to permit a passage of fluid therepast upon a movement of said first valve member away from the inlet of said chamber means, said first valve member including means defining a first valve face adapted to engage said first valve seat to prevent a flow of fluid therepast;

means for biasing said first valve member to the inlet end of said chamber means to effect a restriction of the flow of said fluid past said valve, said biasing means including a first spring member for urging said first valve face means into engagement with said first valve seat; and

fluid flow rate sensing means mounted internally of said first valve member for sensing the flow rate of said fluid and producing a signal in response to a predetermined flow rate, said switching means being responsive to said signal for controlling the activation of said second pumping means.

2. A valve according to claim I, wherein said first valve member includes means defining a second valve seat on the interior thereof adjacent an end thereof and said first valve face means; and

wherein said fluid flow rate sensing means comprises a hollow sleeve member concentric with said first valve member slidably disposed in the interior of said first valve member, said sleeve member having a second valve face thereon adapted to engage and move away from said second valve seat, said second valve seat limiting in one direction the relative sliding movement between said hollow sleeve and said first valve member, said hollow sleeve member having means blocking one end and switch engaging means thereon movable therewith, a movement of said hollow sleeve member away from said second valve seat effecting a movement therewith of said switch engaging means and an activation of said switching means and said second fluid pumping means in response thereto; and

including a second spring member for biasing said second valve face on said hollow sleeve into engagement with said second valve seat. said second spring member being of less strength than said first spring member.

3. A valve according to claim 2, wherein said fluid flow rate sensing means includes a third spring member for urging said second valve face into engagement with said second valve seat, said third spring member being 12 of less strength than either of said first and second spring member; and

further including means defining a fluid passageway from the interior of said hollow sleeve member to the exterior of said first valve member and located between said blocking means and second valve face means.

4. A valve according to claim 2, wherein said switching means comprises means defining an actuator arm adapted to be engaged by said switch engaging means and moved to a position to activate said second fluid pumping means.

5. A valve according to claim 2, wherein said body means includes means defining a second inlet port adapted to be connected to the outlet of said second pumping means, said second inlet means being connected directly to said outlet port.

6. A valve according to claim 1, including adjusting means for adjusting the fluid flow rate sensing means and controlling the rate of flow which will effect a production of said signal.

7. A valve for use in a system having a source of fluid, a first fluid pumping means operative by a driving mechanism and a second auxiliary fluid pumping means and switching means responsive to a change in the flow condition of said fluid caused by a lack of proper performance of said first fluid pumping means to effect an activation of said second fluid pumping means, said valve comprising:

means defining a body having a pair of inlet ports and an outlet port spaced from said inlet ports, said first pumping means being connectible in circuit with one of said pair of inlet ports, said second pumping means being connectible in circuit with the other one of said pair of inlet ports;

chamber means located in said body and between and in fluid communication with said pair of inlet ports and said outlet port;

normally closed valve means in said chamber means for controlling the main flow of fluid from said first pumping means to said outlet port and being openable in response to a predetermined pressure differential in said fluid at said one of said inlet ports and said outlet port, said normally closed valve means being closed, in addition to said normal closing thereof, in response to a fluid flow from said second fluid pumping means; and

fluid velocity sensing means on said normally closed valve means for sensing the velocity of said fluid entering said chamber from said first pumping means and producing a signal in response to a predetermined flow velocity value, said switching means being responsive to said signal for control ling the activation of said second pumping means whenever said flow velocity is at said predetermined value.

8. A valve according to claim 7, wherein said one of said pair of inlet ports includes means defining a narrow crosssectional opening, said chamber means being larger in cross section than said narrow opening and means defining a valve seat adjacent the junction between said narrow opening and said chamber means;

wherein said normally closed valve means includes means defining a valve face thereon movable into and out of engagement with said valve seat; wherein said fluid velocity sensing means includes projection means on said normally closed valve means projecting into said narrow opening, said 13 projection means and said narrow opening defining a fluid restriction gap therebetween so that a flow of fluid from said first pumping means will generate fluid pressure and a movement of said normally closed valve means to an opened condition whereat said projection means is removed from within said narrow opening and a fluid pressure drop across said normally closed valve means is minimal; including resilient means for biasing said projection means into said narrow opening in response to a decrease in the velocity of said fluid, said move ment into said narrow opening defining said signal; and wherein said switching means is responsive to said movement to activate said second pumping means. 9. A valve according to claim 7, wherein said chamber means includes means defining a first valve seat adjacent said one of said pair of inlet ports;

wherein said normally closed valve means is hollow and includes means defining a valve face adapted to engage said valve seat to prevent a flow of fluid therepast; and wherein said fluid velocity sensing means is mounted internally of said normally closed valve means for sensing the flow rate of said fluid and producing said signal in response to a predetermined flow rate, said switching means being responsive to said signal for controlling the activation of said second pumping means. 10. A valve for use in a system having a source of fluid, a first fluid pumping means operative by a driving mechanism and a second auxiliary fluid pumping 14 means and switching means responsive to a change in the flow condition of said fluid caused by a lack of proper performance of said first fluid pumping means to effect an activation of said second fluid means, said valve comprising:

means defining a body having a pair of inlet ports and an outlet port spaced from said inlet port, said first pumping means being connectible in circuit with one of said pair of inlet ports, said second pumping means being connectible in circuit with the other one of said pair of inlet ports;

chamber means located in said body means and between and in fluid communication with said pair of inlet ports and said outlet port;

a first elongated hollow valve member slidably disposed in said chamber means and being adapted to permit a passage of fluid therepast from said first pumping means upon a movement of said first valve member away from said one of said pair of inlets of said chamber means;

means for biasing said first valve member to restrict said one of said pair of inlet ports of said chamber means to effect a restriction of the flow of said fluid past said first valve member; and

fluid flow rate sensing means mounted internally of said first valve member for sensing the flow rate of said fluid from said first pumping means and pro ducing a signal in response to a predetermined flow rate, said switching means being responsive to said signal for controlling the activation of said second pumping means. 

1. A valve for use in a system having a source of fluid, a first fluid pumping means operative by a driving mechanism and a second auxiliary fluid pumping means and switching means responsive to a change in the flow condition of said fluid caused by a lack of proper performance of said first fluid pumping means to effect an activation of said second fluid pumping means, said valve comprising: means defining a body having an inlet port and an outlet port spaced from said inlet port; chamber means located in said body and between and in fluid communication with said inlet port and said outlet port, said chamber means including means defining a first valve seat adjacent said inlet port; a first elongated hollow valve member slidably disposed in said chamber means and being adapted to permit a passage of fluid therepast upon a movement of said first valve member away from the inlet of said chamber means, said first valve member including means defining a first valve face adapted to engage said first valve seat to prevent a flow of fluid therepast; means for biasing said first valve member to the inlet end of said chamber means to effect a restriction of the flow of said fluid past said valve, said biasing means including a first spring member for urging said first valve face means into engagement with said first valve seat; and fluid flow rate sensing means mounted internally of said first valve member for sensing the flow rate of said fluid and producing a signal in response to a predetermined flow rate, said switching means being responsive to said signal for controlling the activation of said second pumping means.
 2. A valve according to claim 1, wherein said first valve member includes means defining a second valve seat on the interior thereof adjacent an end thereof and said first valve face means; and wherein said fluid flow rate sensing means comprises a hollow sleeve member concentric with said first valve member slidably disposed in the interior of said first valve member, said sleeve member having a second valve face thereon adapted to engage and move away from said second valve seat, said second valve seat limiting in one direction the relative sliding movement between said hollow sleeve and said first valve member, said hollow sleeve member having means blocking one end and switch engaging means thereon movable therewith, a movement of said hollow sleeve member away from said second valve seat effecting a movement therewith of said switch engaging means and aN activation of said switching means and said second fluid pumping means in response thereto; and including a second spring member for biasing said second valve face on said hollow sleeve into engagement with said second valve seat, said second spring member being of less strength than said first spring member.
 3. A valve according to claim 2, wherein said fluid flow rate sensing means includes a third spring member for urging said second valve face into engagement with said second valve seat, said third spring member being of less strength than either of said first and second spring member; and further including means defining a fluid passageway from the interior of said hollow sleeve member to the exterior of said first valve member and located between said blocking means and second valve face means.
 4. A valve according to claim 2, wherein said switching means comprises means defining an actuator arm adapted to be engaged by said switch engaging means and moved to a position to activate said second fluid pumping means.
 5. A valve according to claim 2, wherein said body means includes means defining a second inlet port adapted to be connected to the outlet of said second pumping means, said second inlet means being connected directly to said outlet port.
 6. A valve according to claim 1, including adjusting means for adjusting the fluid flow rate sensing means and controlling the rate of flow which will effect a production of said signal.
 7. A valve for use in a system having a source of fluid, a first fluid pumping means operative by a driving mechanism and a second auxiliary fluid pumping means and switching means responsive to a change in the flow condition of said fluid caused by a lack of proper performance of said first fluid pumping means to effect an activation of said second fluid pumping means, said valve comprising: means defining a body having a pair of inlet ports and an outlet port spaced from said inlet ports, said first pumping means being connectible in circuit with one of said pair of inlet ports, said second pumping means being connectible in circuit with the other one of said pair of inlet ports; chamber means located in said body and between and in fluid communication with said pair of inlet ports and said outlet port; normally closed valve means in said chamber means for controlling the main flow of fluid from said first pumping means to said outlet port and being openable in response to a predetermined pressure differential in said fluid at said one of said inlet ports and said outlet port, said normally closed valve means being closed, in addition to said normal closing thereof, in response to a fluid flow from said second fluid pumping means; and fluid velocity sensing means on said normally closed valve means for sensing the velocity of said fluid entering said chamber from said first pumping means and producing a signal in response to a predetermined flow velocity value, said switching means being responsive to said signal for controlling the activation of said second pumping means whenever said flow velocity is at said predetermined value.
 8. A valve according to claim 7, wherein said one of said pair of inlet ports includes means defining a narrow crosssectional opening, said chamber means being larger in cross section than said narrow opening and means defining a valve seat adjacent the junction between said narrow opening and said chamber means; wherein said normally closed valve means includes means defining a valve face thereon movable into and out of engagement with said valve seat; wherein said fluid velocity sensing means includes projection means on said normally closed valve means projecting into said narrow opening, said projection means and said narrow opening defining a fluid restriction gap therebetween so that a flow of fluid from said first pumping means will generate fluid pressure and a movement of said normally closed valve means to an opened condition whereat said projeCtion means is removed from within said narrow opening and a fluid pressure drop across said normally closed valve means is minimal; including resilient means for biasing said projection means into said narrow opening in response to a decrease in the velocity of said fluid, said movement into said narrow opening defining said signal; and wherein said switching means is responsive to said movement to activate said second pumping means.
 9. A valve according to claim 7, wherein said chamber means includes means defining a first valve seat adjacent said one of said pair of inlet ports; wherein said normally closed valve means is hollow and includes means defining a valve face adapted to engage said valve seat to prevent a flow of fluid therepast; and wherein said fluid velocity sensing means is mounted internally of said normally closed valve means for sensing the flow rate of said fluid and producing said signal in response to a predetermined flow rate, said switching means being responsive to said signal for controlling the activation of said second pumping means.
 10. A valve for use in a system having a source of fluid, a first fluid pumping means operative by a driving mechanism and a second auxiliary fluid pumping means and switching means responsive to a change in the flow condition of said fluid caused by a lack of proper performance of said first fluid pumping means to effect an activation of said second fluid means, said valve comprising: means defining a body having a pair of inlet ports and an outlet port spaced from said inlet port, said first pumping means being connectible in circuit with one of said pair of inlet ports, said second pumping means being connectible in circuit with the other one of said pair of inlet ports; chamber means located in said body means and between and in fluid communication with said pair of inlet ports and said outlet port; a first elongated hollow valve member slidably disposed in said chamber means and being adapted to permit a passage of fluid therepast from said first pumping means upon a movement of said first valve member away from said one of said pair of inlets of said chamber means; means for biasing said first valve member to restrict said one of said pair of inlet ports of said chamber means to effect a restriction of the flow of said fluid past said first valve member; and fluid flow rate sensing means mounted internally of said first valve member for sensing the flow rate of said fluid from said first pumping means and producing a signal in response to a predetermined flow rate, said switching means being responsive to said signal for controlling the activation of said second pumping means. 